Compressor cooling system



Aug. 9, 1932. *'B s, AIKMAN 1,870,219v

COMPRES SOR COOLING SYSTEM Filed Jan. 19, 1929 4 Sheets-Sheet l Aug. 9, 1932.

` B. s. AxKMAN COMPRESSOR COOLING SYSTEM Filed Jan. 19, 1929 4 Sheets-Sheet 2 :mmm ....m..

ug- 9, 1932 B. s. AIKMAN 'n 1,870,219

COMPRESSOR OOLING SYSTEM Filed Jan. 19, 1929 4 seets-sheet 3 ug. 9, 1932. B. s. AIKMAN COMPRESSOR COOLING SYSTEM 4 Sheets-Sheet 4 Filed Ja n. 19, 1929 Patented Aug. 9, 1932 UNTE FS PTET OFFECE BURTON S. AIKMAN, OF MILWAUKEE, WISCONSIN, ASSIGNOR T .NATIONAL BRAKE & ELECTRIC CO., 0F MI'NUKEE, VIISCONSIN, A. CORPORATION OE WISCONSIN GOltIPRESSOR COOLING SYSTEIVI applic-saba ined January 1a, i929. seriai No. 333,692.

My invention relates to air compressors in'general, and more particularly to a method of and means for controlling the temperature of the same.

There is at the present time a. growing demand for a compressor of small size and large capacity, and operating at relatively high speed. @ne of the chief diiiiculties that present themselves in the design of com- V pressor to meet these requirements is that of preventing overheating of the compressor. It is known that the greatest diiiiculty in cooling is at the head end of the compresser. In the design of sleeve valve compressor disclosed in my prior Patent No. 1,811,868 the cooling of the cylinder is adequately accomplished.

In continuous duty compression the discharge valve chamber is subjected to exceedingly severe duty. The hot gases are in constant contact With the discharge check valve and its chamber, and unless provision is made for adequately cooling there is a tendency for the temperature to build up to a point Where the lubricating oil carried over is carbonized on the discharge checl; valve which then begins to leak. rIhis further builds up the temperature, and even if the lubrication of the cylinder Walls is not affected it results in overheating of the check valve and destruction of the same.

In my copending application, Serial No. 180,433 of April 2, 1927 I disclose the broadly neviT principle of introducing a cooling medium, either a gas, vapor or liquid, directly into the bodv of compressec air which is in Contact with the exhaust valve, or internally of the valve chamber. Preferably this is accomplished by using some of the compressed air cooled in a radiator and injecting the same into the valve chamber.

The improvement shown in my copending application Serial No. 181,104, Vfiled April th, 1927, is a special form of the above application No. 180,433. In the latter application I have enlarged the exhaust valve chamber to a size rWhere it acts as its own radiator, i. e., throivs olf sufficientheat that the temperature of the gas in contact With the exhaust valve Will not carbonize lubricating oil. As an additional active agent I employ a body of liquid in contact With the cylinder head and discharge valve passage and the shell surrounding the discharge valve.

The Water is a superior cooling medium because of its high specific heat and because its boiling point even under the pressure of the compressed air (100 lbs. to 150 lbs. per square inch) is Well below the temperature of carbonization of the oil.

In the device of said lat-ter application gravity circulation is mainly relied upon for both the air and the Water in liquid and vapor form. In the preferred embodiment of the former application positive circulation is set up.

Noiv in accordance with the present invention I employ the advantages of both systems, i. e., I provide a body of Water because of its large heat conveying power and create a positive circulation in accordance with the teachings of the iirst application. rlhereby I secure a compact system of cooling Which is highly eilicient and positive in action.

lvhereas in the first aforesaid application I bring the cooling Water into contact only with the shell outside of the discharge valve and in the second application bring the cooling medium into Contact only with the inside of the valve chamber and the valve, I now combine these features in the present invention and cause the cooling medium, air and Water, to cool the outside of the valve chamber, the inside of the valve chamber and the valve itself.A

By this combination the maximum temperature of the valve and chamber is not reached unt-il the Water reaches its maximum temperature for as long as the Water is below its maximum, it is effect-ive as a cooling agent.

Also Whereas in the device of the second application the receiver was mounted upon trie top of the compressor or at least above it, a position not wholly advantageous, the present invention permits me to mount the motor and compressor upon the receiver or at any convenient position above the bottom of the receiver.

According to the present invention I provide a novel method of securing a positive circulation of the cooling liquid to carry it to the discharge valve chamber and discharge valve. I provide an automatically operated um or e'ector for movin@ the coolin li uid. This pump or ejector preferably takes the form of a liquid trap or chamber filled by gravity through a port opening into a body of liquid contained in or communicating with the bottom of the receiver and emptied successively by the discharge impulses of the compressor.

The liquid is then carried with the current of the` air discharged by the compressor to a chamber in thermal Contact with the cylinder head and the discharge valve port and discharge valve chamber. Here the liquid may and preferably does separate out of the current of air and is trapped in contact with the parts to be cooled. From this trap or chamber liquid is fed by gravity directly into the discharge valve chamber and into contact with the discharge valve.

This trap or chamber being elevated above the receiver can automatically be drained by gravity so that freezing will not block the discharge valve and cause stalling of the compressor or injury to the same. In the device of application Serial No. 181,104 the liquid did not communicateI directly with the discharge valve and obviously if such communication had been provided there would have been danger of freezing and blocking the discharge valve. Also in case of a leaky discharge valve the Water might all have been driven into the compressor cylinder.

In the present device the amount of water trapped in the upper chamber and which could leak into the cylinder is very small and furthermore drains rapidly back into the receiver. Provision has been made whereby freezing of the water in the receiver does .notI have any injurious effect. The heat developed by the compressor is utilized to thaw out suiicient ice to start the cooling system intooperation. The system is, therefore, not affected by atmospheric changes and continues to function after once being set into operation. In practice the moisture of the airk compressed makes up more water than passes out the discharge. I have, therefore, provided a drain to draw off any excess liquid. Obviously this drain can be automatically operated by a trap `valve if desired. By drawing liquid from the top down, the iilm of oil which tends to accumulate on the water due to oil being carried over in the compressed air is skimmed oif and automatically discharged.

Now in order to acquaint those skilled in the art with the manner of constructing and operating a device embodying the principles of my invention, I shall describe in connection with the accompanying drawings a specific embodiment of the same.

In-the drawings: Y Y

Fig. lis a side view Vpartly in section showing an embodiment Vof the invention;

Fig. 2 is an enlarged fragmentary cross sectional view of the compressor head, discharge valve, discharge chamber and coolng chamber surrounding the discharge chamer; Y

Fig. 3 is an enlarged fragmentary cross sectional view showing the water trap and auxiliary discharge valve.

Fig. 4 is a diagram of an embodiment of my invention employing an open circuitfor the cooling water;

Fig. 5 is a diagram of a system like Fig. 4 but having a closed liquid circuit.

Fig. 6 is a sectional side view of a multicylinder embodiment of my invention;

Fig. 7 shows a modified form of a water trap for use with multicylinder embodiment of my invention; and

Fig. 8 is a section view of another modification of the water trap. Y

Referring now to Figs. 1, 2, and 3, the compressed air storage tank 1 is preferably a cylindrical tank laid on its side and resting in aY pair of saddle brackets 2. A base plate 3 rests on the upper side of the tank 1 and is held secure by means of four spindle bolts 5 which pass through lugs or ears on the brackets and on the four corners of the base plates 3 in a well known manner. The tank 1 is provided with a discharge connection 6 which leads to the point of consumption of the compressed air. A drain valve 7 is provided in the bottom of the tank 1, this drain valve having a nipple or stand pipe 8 extending a short distance above the bottom of the tank for the purpose of retaining a body of Water 9 Ain, the bottom of the tank. The action of the compressor condenses water from the moisture entrained in the air taken into it, so that the supply of water 9 is replenished automatically.

By opening of valve 7 any excess of water above the level of the top of the stand pipe 8 is removed. The valve 7 could be replaced by an automatically operating trap valve to keep the level of the water 9 substantially constant.

A certain amount of lubricating oil leaks past the compressor piston and is carried over into the receiver either asa vapor or emulsilied in the cooling water. This oil coats the interior or the receiver with a thin film, thereby reducing rusting of the receiver walls. Excess oil forms as a lm over the surface of the cooling Water, that film being skimmed off by draining through stand pipe 8. In this manner the air discharged from the pipe 6 is substantially free from the oil drops which have heretofore injured the rubber parts of pneumatic tools.

On top yof the base plate 3, the driving motor 10 and the compressor 11 are mounted with their shafts in alignment. The motor is connected directly to the flywheel 12 oi the compressor 11 through a suitable flexible coupling. lf preferred, the motor and compressor may be mounted with their shafts substantially parallel with a belt connection between them.

The circuit of the motor 10 is controlled by a pressure regulator (not shown) which connects and disconnects the moto-r to and from a source of current as the pressure decreases or increases below or above certain pressure limits, as is well understood by those skilled in the art.

The compressor 11 has a cylinder frame 14 in which a sleeve valve 15 is operated by ring friction b-y the piston 16, which o-perates within the sleeve valve. The structure of the compressor is substantially that shown in my prior Patent No. 1,611,866.

The cylinder frame 14 has a head 17 bolted thereto by means of bolts (not shown). The head 17 has an annular valve seat 18 in the form of a thin relatively resilient metallic ring, the outer edge of which is clamped by means of the clamping ring 2O against the adjacent surface of the head 17, the inner edge of the ring being relatively free and overlying` a small annular recess 19 in the underside of the head 17, as best shown in Fig. 2. The clamping ring 2O is secured to the underside of the base of the head 17 by machine screws 21. The upward movement of the sleeve valve 15 is limited by the upper part of the valve striking against the valve seat 18. The sleeve valve 15 has a collar or ring 22 formed thereon to engage a suitable stop at the top of the cylinder for limiting the downward motion of the valve.

The head 17 has a conical discharge passageway 23 defined by the lower neck portion of walls 24 within the head, this conical passageway leading into a discharge valve chamber 25 defined by the upper bulged portion of walls 24.

The conical discharge passageway 23 receivesthe dome 16 projecting from the top of the cylinder 16 to reduce clearance to a minimum. A discharge valve 26 in the form of a thin circular disc seats over the port formed at the upper end of the passageway 23. A plug fitting 27 is threaded into the threaded socket 28 closing the top of the chamber 25. This fitting 27 has a barrel 29 extending down within a. short distance from the discharge valve 26 to limit the movement of the valve, the valve 26 being provided with several projecting ears 26 which are guided in a cylindrical bore in the chamber about the valve seat and engage the lower end of the barrel 29 at the limit of the valves motion. Within the bar rel 29 a coil spring 30 is positioned. This spring 30 bears down upon the discharge valve 26 and holds the same normally upon its seat.

The air discharge pipe 31 is threaded into a pipe socket 32 provided in the head 17. This pipe socket 32 communicates with the interior of the discharge valve chamber 25 through the passageway 33 defined by walls 34 which are preferably integral with and form a continuation of walls 24.

The outer walls of the. head 17 enclose the chamber 35 adjacent to and substantially surrounding the discharge valve chamber 25 and passageway 33. An inlet pipe 36 is threaded into pipe socket 37 which leads into the chamber 35 at the top of the head 17 directly above the upper portion of wall 34.

An outlet pipe 38 is threaded into a pipe socket 39 which leads from the chamber 35 through the outlet port 39 at the lower left hand side of the head 17.

A transverse wall 40 is provided in the chamber 35 a short distance in front of the outlet port 39. This wall 40l has a small drain passageway 40 at the bottom, the top of the wall extending to within a short distance of the top of the head 17 This wall 40 extends completely across the head and denes a trap for water, which holds water carried into it by the air from pipe 36 in contact with the discharge check valve chamber and its outlet 34. The wall 40 forms a dam defining the norma-l level of water in the trap.

Several small drill holes 41 are provided in the lower portion of walls extending in l an upwardly direction and leading from the water trap in the chamber 35 into an annular recess 42 in the discharge chamber side of walls 24. A fiat annular ring shaped valve 43 fits rather loosely in the recess 42, and

normally covers the top ports of the drill holes 41, serving as a check valve therefor.

This check valve 43 need not be used as it has been found that the main valve 26 functions properly without it. In fact it is often better to omit the valve 43 since its omission permits draining of the chamber 42 thereby lessening the likelihood of the Valve 26 freezing shut when the compressor is shut down.

The outlet pipe 38 leads through suitable pipe connections to the top of the tank at the left end thereof, looking at F ig. 1, threading into a pipe socket or flange 44. The two pipes 31 and 36 are connected as by unions to pipes 45 and 46, respectively, which pipes extend through packing glands 47 in the top wall of the tank near the right hand end thereof. The pipes 45 and 46 extend down to near the bottom of the tank beneath the level of the body of water 9, where they thread into two threaded openings or pipe sockets 48 and 49 in the water intake trap 50.

The water trap or valve 50 comprises a U-shaped casting having the two pipe socket openings 48 and 49 leading into a chamber 51V separated by the wall 52 into connected sections. The chamber 51 is open at the bottom, into which opening an annular ring fitting 53 forming an inletV valve seat is threaded. This ring 53 has an outer upwardly extending flange 55 which bears against a laterally extending iiange 56 on the valve casting to form a tight seat and has an inner upwardly extending ilange 57 which 'forms a seat for a disc valve 58 which forms an automatic inlet check valve. movement of the disc valve 58 is limited by engagement of the wings 58 of valve 58 with the flange 56. Two shallow drill holes 59 are provided in the bottom face of ring 53 to aid in threading the ring 53 into position.

A loaded by-pass valve GO is inserted in the pipe 45 just above the level oi' the body of water 9 in the tank. This valve is in the form of a T having double pipe socket connecting the two sections of pipe 45, and having a hollow laterally projecting boss 61, the interior of which has a passageway 62 leading into the interior of the valve. A ball valve 63 seats over the opening 62, and is held against its seat by coil spring 64 which is held in position by a cotter pin 65 passing through perforations in the wallsof the hollow boss 61.

The operation of the system is as follows: Assume that the piston 16 has just completed its upward discharge stroke, and is beginning its downward intake stroke. Vith the initial downward movement of piston 16 sleeve valve 15 opens, and as the piston continues to move downward a charge oi' air is taken in through the intake port 15. lilith the initial upward movement of the piston 16 sleeve valve 15 closes, and as the piston 16 moves upward the gas is compressed. During the intake stroke, and while the gas in the cylinder is being compressed, valve 58 in the water trap 50 is opened by the submergence pressure of the body of water 9 thereupon, and a quantity of water Hows around the valve into the chamber 51. When the air pressure of the air entrapped above the piston 16 exceeds the pressure in the tank plus tbc pressure of spring 30 holding the valve 26 on its seat, valve 26 is opened, being forced against the end of the barrel 29. As soon as valve 26 opens, the pressure in pipe 45 rapidly increases, and as a result the valve 58 in the water trap 50 is closed it it has not previously closed by gravity, and the water entrapped above the valve 58 is then forced up by the charge of compressed air through pipe 46 and pipe 36 into the cooling chamber 35 around the outside walls of discharge chamber 25 and passageway 33 and is trapped by the dam 40. The charge of compressed air passes over the top of the baille wall 40 and through pipe 38 into the top of the tank 1.

The water trapped by the dam 40 exerts The upward a submergence pressure upon the check valve 43 controlling the ports 41-41, and as soon as the pressure of the stroke has equalized, water enters the channel 42 in direct contact with the edge of the discharge check valve seat and the valve 26. The amount of water that can pass into the discharge check valve chamber is limited by the size and number of passageways 41-41 and the period betwen strokes, and may be controlled in accordance with the design of the device.

At the commencement of the intake stroke of piston 16, valve 26 again closes under the action of spring 30 and the pressure in the chamber 25. Since the gas pressure in chamber 25 and chamber 35 quickly equalize, the weight of the water in chamber 35 raises the ring valve 43 and water passes through the ports 41-41 and enters the discharge check valve chamber cooling the valve and valve seat. If the ports are hot the water is vaporized and carried od with the next discharge stroke. When the piston is again moved upward to develop suilicient pressure within the cylinder to open the valve 26, the pressure in chamber 25 again rises and ring valve 43 is forced down upon its seat, closing orf the ports at theend of drill holes 41. The compressed airas it rushes past the valve 26 is deflected downward somewhat into the recess 42, and as a result the water entrapped above the valve 43, unless it has previously been vaporized, is forcibly blown out against the inner surfaces of walls 24 and 34 where it effectively oools the walls of chamber 25 and passageway 33 internally, whether in the form of water or vapor.

The force of the charge also forces the water entrapped in trap 50 in the meantime out through pipes 46 and 36 into chamber 35, as previously described. The charge of compressed air as it passes through chamber 35 and through pipe 38 carries with it the water vaporized in cooling the outer walls of chamber 25 into tank 1 where it is condensed and cooled. The water that is vaporized inchamber 25 is carried down pipe 45 into contact with the water in trap 50, which is always kept cool by the relatively large radiating capacity of tank 1. Thus a constant forced circulation is maintained in the chamber 25, and a stream of cooled -air and water is vpassed through and in contact with the chamber.

The time interval between the discharge strokes is relatively small when operating the compressor at high speed, but by making the lower opening in the Water trap 50 relatively large with a correspondingly large valve having small lift, a relatively large amount of water can enter the chamber 51 in a short space of time. This'can be controlled by the design. The baille or wall 52 extends down toward valve 58 to define a relatively narrow passageway so that the velocity of the air past th-is point, the lowest part of the passageway, will be relatively high so as to entrain a maximum of liquid, particularly if the amount in the trap should be small.

Thus it will be seen that I have devised an arrangement for cooling the discharge valve and discharge valve chamber externally and internally with a cooling liquid simultaneously, and have devised an arrangement for utilizing the force of the charge of compressed air to obtain a forced circulation of cooling liquid around the outer surface of the discharge chamber and for spraying the cooling liquid against the inne-r surfaces of the discharge chamber.

Another important feature of my invention is in the provision of means for preventing any detrimental result following the starting of the compressor when the water in the tank 1 and in the trap 50 is frozen. First it should be noted that the baffle wall 40 is provided with a small passageway 40 through which the water in the cooling chamber 35 drains by gravity. rlhis passageway is constantly open and a continual drain occurs at this point. Since the incoming supply is in excess of the drain while the compressor is running, the presence of this open drain does not aifect operations. However, when thecompressor is stopped the trapped liquid promptly drains. The drain port should be below the level of the check valve 26 so that no liquid will remain in contact with valve 26 or where upon 'freezing it could block operation of said valve. It is not necessary that all the water be drained out of the head so long as it does not block the valve 26.

Even though the compressor is exposed to freezing temperature when not being operated, so that the ywater in the tank l and in the water trap 50 freezes, the compressor may nevertheless be started in this condition without any preliminary conditioning. lWith the water in the well 50 and in the tank l in a frozen condition, the initial charge of compressed air when the compressor is operated will be prevented from passing the trap 50 and up through pipe 46 and into chamber 35.

Under these conditions, the auxiliary relief valve 60 comesinto action. Under ordinary operation this valve is inactive since the tension in spring 64 exerts a greater force on ball 63 than the difference between the pressure in pipe 45 and tank l. l/V hen the normal outlet through pipe 46 is blocked, as by freezing of water in trap 50, sufficient pressure builds up in pipe 45 at each compression stroke, however, to open valve 60.y The charge of compressed air then enters tank l through port 62. By reasons of the abnormally high pressures developed in pipe 45 under these conditions, only a few discharges through valve 60 are required before the pipe 45 and the valve 60 become relatively hot. The heat generated is carried down by convection to the lower section of pipe 45 and to the water trap 50. The ice in the water trap 50 as well as the ice around pipe 45 and around the water trap 50 soon melts from the transmitted heat of the metal parts so that within a short time the normal path for the discharge is established through pipe 46 and into chamber 35, whereupon valve 60 again becomes inactive.

It will readily be appreciated that the thawing of the ice in and around the trap 50 can be hastened somewhat if the pipe 45 and the pipe below the valve 60 are made of copper. The increased thermal conductivity of copper brings the heat from the compressed air to the ice at a more rapid rate to hasten its thawing. The use of copper pipe as noted is desirable although an iron iipe may most generally be used satisfactorily.

While I have shown, in Figures 1 and 2, my cooling system applied to a particular type of compressor, it is equally applicable to an ordinary water jacketed compressor. In this application of the invention, the output manifold of the compressor is connected to the pipe 3l leading to the water trap 50, and the pipe 36 is connected to the input opening of the water jacket. `The pipe 33 7 s connected to the output opening in the water jacket.

lfhile I have shown in the embodiment of Figs. l, 2 and 3 a system in which the liquid circuit for the cooling liquid is a closed circu't so that the same water is used over and over again, and this is the preferred embodi ment, it is obvious that the liquid circuit may be an open circuit. f

I have operated such a system successfully by injecting a small flow of water directly into the discharge check valve chamber of a compressor, separating the lquid out by a so-called steam trapon the discharge line or connected to the receiver.

In F ig. 4 I have indicated diagrammatically such a system. This system may be applied to compressors already built, and I have found it a practical expedient for cooling compressors which in service tend to overheat.

In Ffg. 4 I have shown a conventional compressor having the usual cylinder head 7l, cylinder 72, piston 73, inlet check valve 74 and discharge check valve 7 5.

The construction of these parts is well known and may be of any preferred or desired form. I have shown the check valves 74 and 75 as poppet valves having stems 7 6 and 77 suitably guided and controlled by springs 7 S and 79 to perform. their proper function. The discharge check valve 7 has a valve chamber SO communicating by way of a discharge passageway 8l wfth a discharge pipe 89 which leads directly or indirectly to the receiver for compressed air.

According to my invention I drill a. small passageway such as indicated at 82 through the metal of the head, this passageway communicating at its inner end wth the interior of the discharage check valve 80 and at its exterior end ending in a suitable pipe socket with the valve and into thermal contact with the inside of the chamber 80.

' Y `The valve 85 may be a needle valve suitable fory regulating the iiow of cooling water into the discharge check valve chamber.

The .discharge pipe 89 is shown yas connected to a receiver 90 which is provided with an automatic trap 86, the function of which is to collect and trap water discharged through the passageway 81 and pipe 82 and periodically to vent the same to atmosphere through a valve ,88 controlled by a iioat 87. The construction of a trap for this purpose is well known, and forms no part of the present invention, the float valve 87 being provided preferably with a snap action whereby the valve 83 is opened and closed with a positive snap action to prevent marginal operation. s

I have found in practice that the application ofsuch a syst-em to compressors which now can be operated only intermittently. because of excessive heating will permit much longer periods of operation or continuous operation without raising the temperature of the head to a point which would car bonize the lubricating oil.

In Fig. 5 I have shown a system employing mechanical injection of water moving in a closed circuit or cycle. In this construction the small water pump 91 is directly driven from the main crankshaft 92 which operates the compressor piston 73. This pump 91 has inlet and disch arge check valves 93 and 94 and a piston 95 operated by a rod 96 and pin 91' on the end of crankshaft 92.

The pump discharge is connected to the water injecting pipe 83 for forcing a predetermined quantity otwater at each stroke into the discharge valve chamber 80. The water carried as a vapor or liquid is in turn driven over into the receiver 90 where the heat thereof is sufficiently dissipated and the water settles into the bottom of the receiver running into trap 9S from whence it passes by inlet pipe 99 to the inlet check valve of' the pump.

When the compressor is idle the pump 91 is idle and stands under equal pressures at each side. Being liquid sealed the leakage is minimized. A diaphragm pump may be employed.

yWhen only a single cylinder compressor is so cooled the pump stroke may be limited to discharge its liquid atk any preferred period of time, preferably while the valve 75 is closed, both to secure more intimate contact with the valve and also to minimize leakage by water sealing the discharge check valve..

This function` of water sealing the discharge check valve assists greatly in preventing back How by leakage into the compressoicylinder and prevents the building up of temperature. Vhere a multi-cylinder compressor isy employed the water dischargev may be manifolded to V,all the cylinders Vor separate pump cylinders may be employed.

IVhile I have shown a hand-operated valve 85 which is employed for regulating the flow, it is to be understood that a suitable orifice restrictionmay be employed in the water line and an automatic valve be em- Y ployed for opening the connection to the source of water supply whenever the compressor vis running. These are refinements which anyone skilled in the art will understand how to utilize.

The compressor shown in Figs. 4 and 5 may be water-jacketed and cooled in the usual way-without interfering withfmy system of cooling. Y

In Figure 0, I show my invention modified for adaptation to a multi-cylinder compressor. f

Thecompressor comprising cylinders 100, 101 and 102 is equipped with a cylinder `head 17 made in accordance with the teachings of my invention. In this modification, the cylinder 102 acts as an elevator to bring water from the trap 50 to the cylinder head. Air compressed by this cylinder is discharged through the valve 26 into the port 33 which Vleads through the pipe 31 to the trap 50, as

shown in Figure 1, the air and water returning through the pipe 36 to the chamber 35. The chamber 35 extends around the valve of the cylinder 102 and also around the valve and discharge connection 104 of the cylinder 101 andthe valve and discharge connection 103 of the cylinder 100. Y The chamber 35 is equipped with the baille 40, which regulates the height'of the water in the chamber. The excess water and the compressed air returned to the cylinder head through pipe 36 pass through the pipe 38 into the receiver, as before. The discharge connections 103 and 104 are manifolded together and connected toY the receiver or tank 1.

The individual valves 26 of the various cylinders are cooled by entrance of water through the ports 41 into the valve chambers as before. It will be noted that, in this modiication, I have omitted the ring valve 43 from the assembly. They may, however, be

employed if desired. The water in the chaml ber 35 is thereby'permitted to flow freely CTI or: (ad

' sion and the lift.

through the ports 41 into direct contact'with the valves 26, and around those valves into the exhaust ports 103, 104 and 33. lVhen the pressure in the exhaust ports is at its maXimum, some air may leak through the ports 41 into the head chamber 35, but it has been found that this leakage is so small as to produce no detrimental effect upon the operation of the system.

In this modification, thecylinders 100 and 101 discharge through ports 103 and 104, respectively, which ports are connected by a manifold, not shown, Which leads directly to the receiver. Thus, it Will be seen that two of the cylinders are compressing directly into the receiver While the third is elevating Water from the receiver to the compressor for cooling purposes.

'Ihe cylinders of the multi-cylinder compressor are Water jacketed by the chambers Which are connected to the chamber 35 by ports, not shown. Obviously, the particular method of cooling the cylinders of a compressor is not involved in the present invention, and the Water jackets shown can be replaced by the usual fins to permit air cooling of the cylinders. The intake valves need not be of the type herein disclosed but may be of conventional form.

In Figure 7 I show a modification of the piping leading to the Water trapy 50, adapting that trap for use With a multi-cylinder compressor. Inasmuch as the valve 58 is relatively large, the time of its operation is so slow that it will not function properly if connected to a multi-cylinder compressor in which all of the cylinders are discharging through the pipe 31. As an alternative method over that shown in Figure 6, I provide the expansion chamber 110 in the discharge pipe 31. The air collected by the discharge manifold leading from all the cylinders of the compressor gradually builds up the pressure in the chamber 110 until it is sufficient to force the Water in trap through the pipe 46 into the Water jacket or j acketed head of the compressor. IVith this accomplished, the pressure in the chamber 110 is lowered sufhciently to permit the valve 58 to open and recharge the trap 50 With water from the receiver.

After a brief interval the pressure in the receiver 110 is built up sufficiently to again discharge the trap 50 into the compressor Water jacket. By this arrangement, the discharge from the compressor is caused periodically to elevate water from the trap into the Water jacket, the periods depending upon the size of the container 110, the rate of compres- The device thus acts as. a pulsomete-r for raising the cooling Water. I have found that with a convenient sized container, a charge of Water is elevated .to the Water jacket upon every'fevv rcycles ofthe compressor, that is,after eachcylinder has In Figure 8, I show a modification of the 'l Water loop pi ses and trap in the receiver. It Will be noted that I have replaced the safety valve 60 by a small port 111 formed as a drill hole, and that I have replaced the Water trap 50 by the return bend 113 in which u the intake port 112 is drilled. ,`When there is no more pressure in the pipe 31 than in the receiver, that is, between strokes of the compressor, Water flows in through the point 112, filling the lower part of the return bend 113. Since this port is formed like a plate orifice, the column of Water in it is short, the inertia of that Water is small and the movement through the port is rapid. When a cylinder of the compressor is discharging and the pressure in pipe 31 increasing, the Water in the trap 113 is raised past the port into'the pipe 16 and thence into the Water jacket of the compressor.

. As soon as this water passes the port 112, there is some leakage of through this port directly into the receiver. However, since the Water in the receiver stands above the port and constitutes a pressure head opposed to this leakage, the amount of leakage is so small as to produce no consequential ede/ct upon the operation of the syste As soon as the one cylinder completes its discharge, the pressure in pipe 31 falls to substantially the pressure of the receiver for a moment and Water rushes in through the port 112 to recharge the return bend 113 in reaciness for the discharge of the next cylinder. It has been found that this arrangement elevates sufficient Water from the receiver to the Water jacket of a tvvo cylinder compressor to perform the desired cooling'. If more than two cylinders are employed I prefer to use the arrangements of F 6 or F 7.

It Will also be noted that in Figure 8 I have n shown the port 111 in place of a safety valve 60. rIhis port permits some air to leak into the receiver when the system is running normally, but the port is small and the amount of such leal-:age is of no consequence` l,"Vhen the return bend 113 is blocked by ice, the air exhausted into the pipe 31 by the compressor escapes through the port 111 into the receiver, thereby preventingthe building up of dangerous pressures in the compressor. rllie modification shown in Figure 3 is simpler than the arrangement shown in Figure 3 and Figure 7, and it has been found that its action is entirely satisfactory. particularly on a tivo cylinder compressor. The pipe 31 which conducts the compressed air into contact with the Water in tank 1 is preferably made of copper to assist in thawing out the bend when it is blocked with ice` although the use of a copper pipe is not absolutely necessary for this purpose.

I am aware that it is old to inject cooling water directly into the cylinder and cause the same to be passed over with the discharged compressed air, but there are certain disadvantages particularly in respect to lubrication in such a system, all of which is completely avoided by my present invention.

I believe it is broadly new with me to discharge water directly into the discharge valve chamber in thermal contact with the discharge valve and its surrounding walls. I believe also that it is broadly new with me to 'water seal the discharge check valve of a gas compressor.

I do not intend to be limited to the details shown and described except as they appear in the appended claims.

' I claim:

1. In combination, a discharge check valve chamber, a housing surrounding the same, a delivery conduit leading from the housing, a pipe leading from the chamber to the housing, and means for introducing a cooling liquid into said pipe.

2. The combination with a compressor having a discharge check valve chamber, of a housing surrounding said chamber, means for trapping liquidin the housing in contact with the chamber, a delivery conduit leading from the housing, a pipe leading from the chamber to a point outside of the housing and back to the top of the housing, and means in said pipe for introducing a cooling liquid into said pipe.

3. The combination with a compressor having a discharge check valve chamber, of a housing surrounding the same, a delivery conduit leading from the housing, a pipe extending from the chamber to a point outside the housing and back to the housing, means for introducing a cooling liquid into said pipe and means for discharging liquid from the housing into the chamber to cool the same.

4. In combination, a discharge check valve chamber, a housing surrounding the same, a delivery conduit leading from the housing, a pipe leading from the interior of the chamberto the outside of the housing and opening into the housing, said pipe having a liquid trap whereby the air discharged from the chamber conveys liquid into the housing. 5. In combination, a discharge check valve chamber, a housing surrounding the same, a

delivery conduit leading from the housing, a

pipe leading from the interior of the chamber y to the outside of the housing and opening into the housing, said pipe having a liquid trap whereby the air discharged from the chamber conveys liquid into the housing, and a check-valved connection between the housing and the chamber for passing cooling liquid from the housing into the chamber.

. 6. `In combination, a discharge check valve chamber, a housing surrounding the same, a delivery conduit leading from the housing for conveymg away compressed gas, a looped pipe leading from the interior of the chamber to the outside of the housing and back to the chamber, said housing having means for trapping liquid in contact with the outside ofy the chamber, and a valve connection between the housing and the interior of the chamber, said looped pipe having means for ooling the vapor discharged from the chamer. f

7. In a compressor, the combination of a head, a discharge valve chamber, a discharge passageway through the head into the chamber, a discharge check valve in the chamber controlling said passageway and a checkvalved port extending through the wall of the chamber for introducing cooling liquid into the chamber.

8. In a .compressor having a head, a discharge check valve chamber having a discharge check valve therein, a trap for liquid surrounding the discharge check valve chamber and a valved inlet port leading from the trap into the interior of the chamber. y

9. In combination, a receiver for compressed air, a compressor mounted above the bottom of the receiver, said compressor having a cylinder head, said cylinder head having a discharge check valve chamber, a disn a trap for liquid about the chamber and a pipey leading from the housing to the recelver for delivering compressed air thereto.

10. In combination, a receiver, a compressor mounted above the bottom of the receiver, said compressor having a cylinder head, said cylinder head'having a discharge check valve chamber, a discharge passageway leading to the chamber, a discharge check valve controlling said passageway, a closed housing about said chamber, a dam in said chamber forming a liquid trap about the chamber, said dam having a drain passageway therethrough, a' conduitleading from the inside of the chamber through the housing and through the wall of the receiver, a valved liquid trap located in the bottom of the receiver and connected to said pipe, a loaded relief valve in said pipe above said trap, a return pipe leading from the trap to the housing, and a pipel leading from the housing to the receiver for delivering compressed air thereto.

11. In combination, a receiver, a motor compressor mounted upon the'receiver, said compressor having a cylinder head, said cylinder head having a discharge check valve chamber, a discharge passageway leading to said chamber, a valve controlling said passagevvay, a closed housing about said chamber, a conduit leading from the inside of the chamber into the interior of the receiver, a valved liquid trap located adjacent the bottom of the receiver and connected to said pipe, a return pipe leading from the trap to the housing, said housing having a dam providing a trap for liquid about the chamber, saiddam having a drain passageway, and a pipe leading from the housing to the receiver for delivering compressed air and excess of liquid from the housing to the receiver.

12. In a compressor, a ydischarge check valve Water sealed against leakage between discharge strokes of compressed air therethrough, and means for introducing said Water While the valve is closed.

13. In a compressor, a discharge valve chamber, a discharge check valve therein, and ,means for injecting a cooling liquid into the chamber, Which liquid seals the said valve to minimize leakage thereof, said means adaptedto be operative at times when the discharge check valve is closed.

14. In combination, a receiver, a compressor mounted above the bottom of the receiver, said compressor having ahead, a discharge check valve chamber in said head, a wall enclosing said chamber and leading to a discharge port, a conduit leading from said port through the Wall of said receiver, a liquid trap located in the bottom of the receiver and connected to said conduit, a relief port in said conduit above said trap, a return pipe leading from the trap to the cylinder head, a second chamber in said head outside o and surrounding said Wall, and a pipe leading from the cylinder head to the receiver for delivering compressed air thereto.

15. In combination, a compressor, a discharge valve chamber enclosed Within a cooling Vchamber having an outlet port, means for conveying liquid into said chamber, and a baie Wall near said port to prevent the ready escape of liquid through said port, said bathe Wall having a small opening near the bottom to drain the cooling chamber When said liquid conveying means is inoperative.

16'. In a gas compressor, a discharge valve, Va tubular shell surrounding the discharge valve, said shell having a seat therein for the valve and an annular recess around said seat, a casing providing a pocket for liquid around the shell, said shell having an opening leading from' said pocket into said recess, and an annular valve loosely disposed in said recess covering said opening for controlling the i'ovv of liquid from said pocket into said recess.

17. In a multicylinder compressor having a head, a` discharge check valve chamber for each cylinder, a discharge check valve in each chamber, a. liquid trap surrounding said chambers, and inlet ports leading from said trap into each of said chambers.

18. In combination With a multicylinder compressor having a head, a discharge chamber and valve i'or each cylinder, a receiver, a Water trap in said receiver, a Water jacket in said head and surrounding said discharge chamber', a delivery conduit connecting the discharge chamber or one of said cylinders to said Water trap, a discharge manifold connecting the chambers of the remaining cylinders to said receiver, a return pipe connecting said water trap to said Water jacket, and a discharge pipe connecting said jacket to said receiver.

19. In combination With a multicylinder compressor having a head, a discharge chamber and a valve for each cylinder, a receiver adapted to contain Icompressed gas and Water, direct connections from the discharge chambers of all but one of said cylinders to said receiver, a Water jacket in said head, a loop connecting said one discharge chamber to said Water jacket, said loop containing means for injecting Water into said Water jacket, and a discharge pipe leading from said Water jacket to said receiver.

20. In combination with a multicylinder compressor having a Water jacket, a discharge chamber for each cylinder, a receiver containing Water, a discharge conduit connecting said discharge chambers through a loop in said receiver to said Water jacket, means including a pulsomotor in said loop for elevating Water from said receiver to said jacket, and a pipe for returning the Water from said jacket to said receiver.

21. In combination With a multicylinder compressor having a Water jacket, a discharge chamber for each cylinder, a receiver containing vvater, a discharge conduit connecting said discharge chambers through a loop in said receiver to said Water jacket, means including an air tank and a Water trap in said loop for causing the air discharged through said conduit to elevate Water to said Water jacket, and a pipe for returning said air and Water to said receiver. Y

22. In a compressor system comprising a compressor and a receiver for compressed air, the method of limiting the temperature ris-e of the compressor which comprises compressing separate charges of gas, discharging said charges free of liquid into the discharge check valve chamber of the compressor, injecting Water into the discharge check valve chamber and into direct thermal contact with the charges of compressed gas passing the discharge check valve, carrying the Water thereby over into the receiver, throwing` ott' the heat from the same, and carrying the cooled Water back intoV the discharge check valve chamber to cool the latter.

23. In` a gas compressor, the method of operating the same to control the temperature rise thereof'which comprises compressing substantially adiabatically successive charges of gas tree of liquid, discharging the heated charges in succession from the compressor cylinder, and introducing a cooling liquid into the heated charges after they leave the compressor cylinder.

24; A compressor comprising, in combination, a cylinder, a piston movable therein, 'valves controlling the intake and discharge of air from the cylinder, conduit means adapted to convey a cooling medium into thermal contact with one of said valves, and means for controlling the flow through said conduit means.

25. A compressor comprising, in combination, a cylinder, a piston movable therein, valves controlling the intake kand discharge of air from the cylinder, a cylinder head forming a valve chamber for the discharge valve, a conduit opening into communication with said chamber adjacent the discharge valve, and controlled means for supplying water under pressure to said conduit, the latter being adapted to convey the water into thermal relationwith the discharge valve to cool the same.

26. In a gas compressor system, in combination, a gas receiver, a compressor operating to drive gas under pressure into said receiver and comprising a cylinder'head, a discharge valve chamber in said head, and a discharge check Vvalve in said chamber, a liquid trap in the receiver, a conduit leading from said trap to said discharge valve chamber, and a pump driven in unison with the compressor for delivering liquid through said conduit into said chamber to cool the valve therein.

27. In a gas compressor system, in combination, a gas receiver, a. compressor operating to drive gas under pressure into said receiver and comprising a cylinder head, a discharge valve chamber in said head, and a discharge check valve in said chamber, and pump means for periodically injecting a mass of cooling `medium into said valve chamber in thermal contact with said discharge valve.

28. In a gas compressor system, in combination,a gas receiver, a compressor operating to drive gas under pressure into said receiver and comprising a cylinder head,y a discharge valve chamber in said head, and a discharge check valve in said chamber, a source of water under pressure, a conduit leading therefrom into said valve chamber for inJecting a supply of water into said valve chamber in thermal contact with said discharge valve to cool the same, and means for controlling the flow of water through said conduit.

29.1K compressor comprising, in combination, a discharge check valve chamber, a housing surrounding the same, a delivery conduit leading from the housing for conveying away compressed gas, a looped pipe leading from the interior of the chamber to the outside of the housing, said looped pipe having means for cooling the vapor discharged from thechamber, and an outlet pipe leading from said housing. f Y

30. In a gas compressor system, in combi-y nation, a gas receiver, a compressor operating to drive gas under pressure into said receiver and comprising a discharge check valve chamber, a housing surrounding the same, a delivery conduit leading from the housing for conveying away compressed gas, a looped pipe leading from the interior of the chamber to said receiver and back to the housing, the loop being in said receiver and havin ort means to permit ingress and egress 0% uid into and from the interior of said pipe, said housing having means for trapping liquid in contact with the outside of the chamber, and a valve connection between the housing and the interior of the chamber.

31. In a gas compressor system, in combination, a gas receiver, a compressor operating to drive gas under pressure into said receiver, said compressor having a cylinder head, said cylinder head having a discharge check valve chamber, a discharge passageway leading to said chamber, a discharge check valve controlling said passageway, a closed housing about said chamber, a conduit leading from the inside of the chamber through the housing and through the wall of the receiver to f the bottom of the receiver, a loop connected to the lower end of said conduit, a return pipe leading from the loop to the housing, said housing providing a trap for liquid about the chamber and a pipe leading from the housing to the receiver for delivering compressed air thereto, said loop having an orilice to permit liquid in the receiver to enter said loop and said conduit having a relief port above the normal level of liquid in said l receiver.

32. In a compressor having a compressor cylinder and a discharge valve chamber, the method of limiting temperature rise of the compresor which comprises compressing gas in the cylinder, discharging the compressed gas free of'liquid into the valve chamber and nJecting cooling liquid into the valve chamer. k33. In a compressor having a compressor cylinder anda discharge valve chamber, the method of limiting temperature rise of the compressor which comprises compressing gas in the cylinder, discharging the compressed gas free of liquid into the valve chamber, in-

jecting cooling liquid into the valve chamber, removing thel gas and liquid .from the valve chamber and cooling them, separating out the liquid and reinjecting the liquid into the chamber. Y

34. In a compressor having a cylinder an ibs iso

a discharge valve the method of limiting the temperature rise of the cylinder and discharge valve Which comprises compressing a charge of gas out of the presence of any cooling liquid in the cylinder, discharging the compressed gas from the cylinder past the discharge Valve and bringing cooling liquid into thermal contact With the gas after it leaves the cylinder.

35.111 a compressor system the method of limiting the temperature rise of the compressor which comprises compressing charges of gas and thereby heating the same, discharging said compressed charges of gas into intimate thermal contact with small amounts of cooling liquid, vaporizing said cooling liqpid7 and carrying the same, With the compressed gas, away from the compressor and cooling the mixture of compressed gas and vapor to the extent of condensing the Vapor to liquid form.

In Witness whereof I hereunto subscribe my name this 31st day of December, 1928.

BURTON S. AIKMAN. 

